For medical materials including physiological and hygienic material etc., especially for catheters and guide wires, low frictional property (easily-slippery property) of the surface is one of the essential requirements. For example, if these materials have no easily-slippery property, when a catheter is inserted in a human body, there is the possibility that a pain could be accompanied with it or a damage or an inflammation of tissue mucosa could occur.
As conventional technologies providing the easily-slippery property, a method wherein the surface of a base material is coated with a variety of oils, a method wherein the surface of the base material is coated with a polymer having a low friction coefficient such as Teflon and a method wherein it is coated with a hydrophilic polymer are in public use. It is understood that especially, coating with a hydrophilic polymer is superior one from the viewpoints of practical use and safety.
As the practical methods for coating with a hydrophilic polymer, fixation of polyvinyl pyrrolidone with an isocyanate (Japanese Patent Laid-Open No.19,582/ 1984, U.S. Pat. No.4,100,309), a method using a hydrophilic polymer copolymerized with a reactive functional group and an isocyanate (Japanese Patent Laid-Open No.81,341/1984), fixation of polyethylene oxide with an isocyanate (Japanese Patent Laid-Open No.193,766/1983) are disclosed.
However, the method wherein the surface of a base material is coated with a variety of oils exhibits low durability and has a problem of safety due to eluates. The method wherein it is coated with a polymer having a low friction coefficient such as Teflon hardly exhibits sufficiently an easily-slippery property. The method of coating with a hydrophilic polymer exhibits an easily-slippery property being superior to these methods but there is a problem on its durability. For example, in fixation of polyvinylpyrrolidone with an isocyanate (Japanese Patent Laid-Open No.19,582/1984, U.S. Pat. No.4,100,309), the bonding between polyvinylpyrrolidone and the base material is not sufficient and an eluation occurs. Furthermore, in an improved method thereof wherein a hydrophilic polymer copolymerized with a reactive functional group and an isocyanate are used (Japanese Patent Laid-Open No.81,341/1984), these are not sufficiently solved. It is estimated that this is caused by a relatively easy hydrolysis of the bonding (amide bondings etc.). Moreover, in the fixation of polyethylene oxide with an isocyanate (Japanese Patent Laid-Open No.193,766/ 1983), there is similarly a problem on its durability.
As described above, there exists no method for providing an easily-slippery property exhibiting both characteristics, durability and safety. Namely, the purpose of the present invention is to offer a technology providing an excellent easily-slippery property which solves the problems of these conventional technologies.